Conventional non-rigid airships have a generally cigar shaped body which maintains its shape by means of internal gas pressure. At least a portion of the internal gas has a density less than that of the ambient air so that the airship is generally weightless. A gondola for carrying passengers is suspended beneath the body of the airship by means of suspension cables extending through the interior of the body of the airship and attached to the top portion of the airship.
Propulsion for conventional airships is provided by means of engines, one of which is usually attached to each side of the gondola. Conventional airships are further provided with control surfaces, namely rudders and elevators, toward the tail section to control vertical and horizontal positioning of the airship.
Traditionally there has not been much latitude for varying the shape of airships as the flight control mechanisms have included elevators, rudders and gondola mounted engines as described. Accordingly, such airships have required generally elongate bodies with the control surfaces mounted toward the rear in the path of the air flowing over the airship. There are situations, however, where different shapes may be preferred. One such example is in advertising. Although advertising logos may be displayed on the sides of the conventional airships, it has not been possible to make the airships in various shapes representative of various manufacturer's products. Such shapes might include beverage cans, spark plugs, etc.
A further disadvantage to the prior designs is that mounting of the propulsion engines to the gondola transmits engine vibration and noise directly into the gondola. Also, traditional airships are rather cumbersome in operation as they are normally incapable of very great speeds so that the use of control surfaces to position the airships gives a generally lazy or slow response to directional input by the pilot. The response of these airships to directional input decreases as their forward speed decreases which, in turn makes such airships difficult to control when landing except at speeds requiring a large ground crew for receiving and mooring the airship.